I've always been curious about something. Chicago is called the city of big shoulders. What does that mean exactly? I've always thought the Sears Tower itself looks like it has big shoulders. Those 90th floor setbacks, I mean. Has anyone ever read anything that suggested that was intentional?

If only the Tower had an architectual spire on it instead of broadcast antennas, this would have most likely remained the tallest completed skyscraper in the world. Either way however; Sears Tower is one of the world's most iconic skyscrapers period!

I've always been curious about something. Chicago is called the city of big shoulders. What does that mean exactly? I've always thought the Sears Tower itself looks like it has big shoulders. Those 90th floor setbacks, I mean. Has anyone ever read anything that suggested that was intentional?

LOL I know what you mean - the silhouette from the West (looking East) resembles a head & shoulders.

The quote is Carl Sandburg:

Hog Butcher for the World
Tool Maker, Stacker of Wheat
Player with Railroads and the Nation's Freight Handler,
Stormy, Husky, Brawling, and City of the Big Shoulders.

Sandburg is celebrating the role that brawn and labor played in the city's explosive rise in the 19th and early 20th centuries.

It would have been cool if these clouds were produced because of its height but I think Seppuko_Panda is right, I took these pics early in the morning at the end of October, it was cold and as these clouds disappeared as the day advanced, so ventilation is a better explanation, probably a cloud of steam due to the difference of temperature;